There is a glitch in lugormod where you can keep getting credits from killing a npc, as long as you have ammo. To see what i mean, place a npc_spawner, give the npc 1 health, and have its npc_target5 fire a target_credits. Spawn the npc, and have one person snipe the npc. Immediately after it dies, use the alternate attack for the repeater (smasher-explosion thing) on the body. Do not let go of the button, and you will see what i mean. You will keep getting credits.

Anyways, how to get around the glitch. It is really simple. Just set the spawner's npc_target to fire a target_teleporter. Put the target_teleporter in the void, or on top of the map. The second the npc is killed, the body will warp away, making this exploit useless.